Inner tube for pneumatic tires



July 5, 1955 Filed Sept. 50. 1952 H. D. HURT INNER TUBE FOR PNEUMATICTIRES 2 Sheets-Sheet l INVENTOR 15C! Sfar-afg Hzlf' ATTORNEY July 5,1955 H, D HURT 2,712,339

n INNER TUBE FOR PNEUMATIC TIRES Filed Sept. 50, 1952 2 Sheets-Sheet 2lll!) INVENTOR Hmfa'f-Ja Huff ATTORNEY United States Patent Thisinvention relates to inner tubes for pneumatic tires, and moreparticularly to a novel and improved inner tube structure of theanti-blowout type particularly suitable for motor vehicles, bicycles,and the like.

A main object of the invention is to provide a novel A still furtherobject of the invention is to provide an improved inner tube of theinternally reinforced type, the reinforcing means being of amultiple-laminate type and employing non-fibrous reinforcing material,whereby blowouts are effectively prevented..

provided with internal self-sealing structure, thereby preventing airleaks around puncturing objects which may penetrate said structure.

A still further object of the invention is to providean and fullyprocessed textile plastic shield layers'which have been oriented andheat-set for adequate dimensional stability, thus assuring a high degreeof blowout protection for the tube.

claims, and from the accompanying drawings, wherein:v

Figure l is a vertical cross-sectional view taken transbroken away, andthe elements of the inner tube being being shown partly in longitudinalvertical cross-section and partly in side elevation.

Figure 3 is a perspective fragmentary view of the inner tube of Figuresl and 2, the tube being shown in crosssection and with parts broken awayto reveal its structure.

Figure 4 is an enlarged fragmentary perspective view of one of the cordelements employed in the reinforcing layers of the inner tube of Figures1 to 3.

Figure 5 is a vertical cross-sectional view similar to Figure l, showinga modified form of inner tube according to the present invention.

Figure 6 is a side elevational view of the fragmentary portion of thetire and tube of Figure 5, the'tire and tube being shown partly brokenaway,-in the same manner as in Figure 2, and showing the elements 0f theinner tube partly in longitudinal vertical cross-section and partly inside elevation.

Figure 7 is a perspective fragmentary view of the inner tube of Figures5 and 6, the tube being shown in cross-section and with parts brokenaway to reveal its structure.

Figure 8 is a .perspective view, similar to Figure 7, showing a furthermodification of the inner tube of the present invention.

Figure 9 is an enlarged cross-sectional detail view taken through theinner tube of Figure 8, transverse to one of the reinforcing bandsthereof.

The improved inner tube of the present invention employs plasticmaterials of the type presently used to produce textile fibres, theplastic materials being herein employed in solidified non-fibrous formfor creating the anti-blowout strain-resisting elements of the innertube. There are many types of such plastic materials now available foruse, some of which are identified by trade greatly increased, whichtherefore provides great resistance to elongation of said elements whensubjected to working stresses while in service.

Referring now to the drawings, and moreparticularly to Figures l to 4,11 generally designates an inner tube said tube being shown installed ina tire 12 having the side Walls 13, 13 which terminate in the beadportions 14, 14. The bead portions 14, 14 are received in the rimelements 15, 15 of a conventional vehicle Wheel 16, the well of thewheel being shown at 17.

The inner tube 11 comprises an inner envelope 18 having an linternallythickened top portion 19 (as viewed in Figure l) and an externallythickened bottom portion 20.I The externally thickened portion 20definesfaf The inner envelopeI pair of external shoulders 21, 21. 18 ispreferably made of material having special punccountered in roadconditions.

Due to the special cross-sectional shape of the envelope 18, a seat isdefined on the outer surface thereof around its tread portion betweenthe shoulders 21, 21. This seat is provided to receive and hold atriple-laminated reinforcing structure, one form of which isspecifically illustrated in Figures l, 2 and 3.

In Figures l, 2 and 3, the triple-laminated reinforcing structurecomprises a central plastic layer 22 having on one side thereof a matrix23 of rubber-like material in which are embedded the diagonallypositioned, side-byside plastic cords 24, and on the other side anotherrubber-like matrix 25 in which are embedded the diego nally positioned,side-by-side plastic cords 26. As shown, the plastic cords 26 extendsubstantially at right angles to the plastic cords 24. The matrices 23and 25, containing their diagonally extending plastic cords 24 and 26,are adherently joined to the central thin plastic sheet 22, which ispre-stretched and oriented in the direction of the tube axis, namely,the circumferential direction of the tube, whereby the direction oforientation (maximum strain resistance) of the sheet 22 is at an angleof 45 degrees to the directions of the respective cords 24 and 26.

The laminated structure above described is placed in the seat definedbetween the shoulders 2l, 21, and then an outer tubular sheath 27 isplaced over the composite whole, said outer sheath being of rubber-likematerial. Following this, vulcanizing heat is applied, thus joining theparts into a unitary single inner tube.

The tube valve is, of course, installed in the tube in a conventionalmanner.

As is illustrated in Figure l, the permanent elastic area comprising theexternally thickened tube portion 2li is arranged so that it will belocated substantially in the well 17 of the wheel so that this elasticarea stretches independently of the reinforced portion of the tube. Thereinforced portion of the tube is arranged to extend inwardly over theannular areas adjacent the joints between the beads 14 and the rimelements 15 to protect the tube against rim cuts.

The cord elements 24 and 26 are made from relatively thin and narrowplastic strip sheet material, or strip section material, such as thestrip material shown at 28 in Figure 4. This strip material is furtherprepared for use by coating same with a plastic binding agent, whichwhen dry, allows the strip sections to be spiraliy twisted so that theyform rounded cord elements 29. After the spiral twisting of theseelements, they are subjected to a high temperature so that they aresealed together on the inside surfaces thereof, thereby providing apermanent rounded shape for the cord elements. The strip material 2S ispreviously oriented and heat-set by conventional methods to providemaximum strain resistance in the longitudinal direction of the strip.

As shown in Figure 4, the strip material 28 is longitudinally grooved orserrated on the outside surface thereof, so that the serrations orgrooves are externally exposed when the strip is twisted, providing anexterior highly eliicient antislip bonding surface.

The inside surface of the inner, gurnmy envelope i3 is preferably coatedwith powder or other substance which is non-tacky at normaltemperatures, thus preventing the interior surfaces of the envelope 18from sticking together prior to use of the tube.

It is known that a considerable temperature increase develops in a tireand in the inner tube contained therein, caused by the rapid flexing ofthese members while in service. The textile plastic materials employedin the triple-laminate reinforcing member has considerably higher heatinsulating properties than rubber or the synthetic substitutes thereforemployed in the inner envelope i3 and the outer tubular sheath 27.Therefore, the reinforcing member is preferably formed with minuteradial perforations 3d extending through the matrices 23 and 25 and theintervening plastic sheet 22, said perforations being distributeduniformly over the reinforcing member and allowing the vulcanizingmaterial to ooze into the perforations, thus providing a locking meansfor anchoring the reinforcing member to the inner and outer elements ofthe tube, as well as providing heat transmission paths for the outwardescape of generated heat from the inside of the laminated reinforcingmember.

Furthermore, the matrix material employed for the matrices 23 and 25 maybe made of known rubber or plastic material having high heatconductivity, so as to rapidly convey excessive generated heat from thetread portion of the inner tube. The outer sheath 27 is preferably madeof rubber-like material having high heat conductivity. This will serveto dissipate and conduct generated heat from the tread portions of boththe tire and the tube laterally away from said tread portions and towardthe metal rim elements 1S, 15.

Referring now to the form of the invention illustrated .a in Figures 5,6 and 7, the triple-laminated reinforcing structure comprises respectiveinner and outer plastic layers 3f and 32, between which is interposed amatrix 33 of rubber-like material containing the uniformly spaced,transversely' arranged plastic cords 34. Cords 34 are formed in the samemanner as the cords 24 and 26 of Figures l to 3, namely, by the processpreviously described in connection with Figure 4. As shown in Figures 5and 7, the cords extend transversely around the reinforcing structuresubstantially from one outer shoulder 2l to the other outer shoulder 21of the inner envelope i8. The plastic sheets 31 and 32 are prestretchedand oriented in the direction of the tube axis, namely, thecircumferential direction of the tube, as in the case of sheet 22 ofFigures l to 3.

The laminated structure comprising sheets 31 and 32,

with the interposed matrix 33, is placed in the seat defined betweenshoulders 2l, 21, and the outer tubular sheath 27 is placed over thecomposite whole, after which vulcanizing heat is applied, joining theparts into a unitary whole, as in the case of the form of the inventionillustrated in Figures l to 3.

Referring now to the form shown in Figure 8, the triple-laminatedreinforcing structure comprises the inner and outer plastic layers 31and 32, between which is interposed a matrix 35 of rubber-like materialcontaining the uniformly spaced, transversely extending plastic bands36. The bands 36 are oriented in a direction parallel to their lengthand are also heat-set for dimensional stability, The plastic sheets 3land 32 are oriented in a direction at right angles to the direction oforientation of the bands 36, namely, the circumferential direction ofthe tube, as in Figures 5, 6 and 7. The plastic bands 36 may have anydesired cross-sectional shape, such as rectangular, parallelogram, orthe like. Merely by way of example, the bands are illustrated as beingof parallelogram cross-sectional shape, as shown in Figure 9.

The triple-laminate structure of Figure 8 is placed in the seat definedbetween shoulders 21, 21 and the outer tubular sheath 27 is placed overthe composite whole, after which vulcanizing heat is applied, joiningthe parts into a unitary whole, as in the previously de- -scribed formsof the invention.

As in the case of the form illustrated in Figures l, 2 and 3, thetriple-laminate reinforcing structures of Figures 5, 6 and 7 and ofFigures 8 and 9, may be formed with the minute radial perforations 30extending through the plastic sheets and matrices of the reinforcingstructures.

rthe bands 36 of Figure 8 may be formed on the opposite faces thereofwith longitudinal ridges or grooves to improve the bond between saidbands and the matrix 35.

While certain specific embodiments of improved internally lreinforcedinner tubes have been disclosed in the foregoing description, it will beunderstood that various modifications within the spirit of the inventionmay occur to those skilled in the art. Therefore it is intended that nolimitations be placed on the invention except as defined by the scope ofthe appended claims.

What is claimed is:

l. In an inner tube, an inner tubular envelope of stretchable elasticmaterial externally thickened at one portion thereof to deiine externalshoulders, a plurality of laminations secured on the external surface ofsaid envelope and extending adjacent said shoulders, at least one ofsaid laminations being substantially non-stretchable in a directionparallel to the major circumferential direction of the tube and anotherof said laminations comprising a matrix of elastic stretchable materialand a plurality of elongated, substantially non-stretchable elementsextending at a substantial angle to said major circumferentialdirection, and an outer tubular envelope of stretchable elastic materialsecured on said laminations and said externally thickened portion of theinner envelope.

2. In an inner tube, an inner tubular envelope of stretchable, gummy,self-sealing elastic material externally thickened at the inner majorcircumferential portion thereof to define external shoulders, aplurality of larninations secured on the external surface of saidenvelope and extending adjacent said shoulders, at least one of saidlaminations comprising a sheet of plastic material which issubstantially non-stretchable in a direction parallel to the majorcircumferential direction of the tube, another of said laminationscomprising a matrix of elastic stretchable material and a plurality ofelongated, plastic, substantially non-stretchable elements extending ata substantial angle to said major circumferential direction, and anouter tubular envelope of stretchable elastic material secured on saidlaminations and said externally thickened portion of the inner envelope.

3. In an inner tube, an inner tubular envelope of stretchable elasticgummy material externally thickened at the inner major circumferentialportion thereof to dene a pair of external shoulders, a triple-laminatereinforcing member secured on the external surface of said envelope andextending adjacent said shoulders, said reinforcing member comprisingthree laminations, at least one of which comprises a sheet of plasticmaterial which is substantially non-stretchable in a direction parallelto the major circumferential direction of the tube and another of whichcomprises a rubber-like matrix having a plurality of side-by-sideelongated, substantially non-stretchable plastic elements embeddedtherein and extending at a substantial angle to said majorcircumferential direction, and an outer tubular envelope of stretchableelastic material secured on said reinforcing member and said thickenedportion of the inner envelope.

4. In an inner tube, an inner tubular envelope of stretchable elasticmaterial, a laminated reinforcing member secured on the external surfaceof said envelope,

one of the laminations of said reinforcing member comprising a sheet ofplastic material which is substantially non-stretchable in a directionparallel to the major circumferential direction of the tube and anotherof the laminations comprising a rubber-like matrix having a plurality ofside-by-side elongated, substantially nonstretchable plastic elementsembedded therein and extending at a substantial angle to said majorcircumferential direction, and an outer tubular envelope of stretchableelastic material secured around said reinforcing member and said innerenvelope.

5. In an inner tube, an inner tubular envelope of stretchable, elastic,gummy material externally thickened at the inner major circumferentialportion thereof to detine a pair of external shoulders, atriple-laminate reinforcing member secured on the external surface ofsaid envelope and extending adjacent said shoulders, said reinforcingmember comprising three laminations, the center lamination comprising asheet of plastic material which is substantially non-stretchable in adirection parallel to the major circumferential direction of the tubeand the other laminations each comprising a rubberlike matrix having aplurality of side-by-side elongated, substantially non-stretchableplastic elements embedded velope.

6. In an inner tube, an inner tubular envelope of stretchable, elastic,gummy material externally thickened at the inner major circumferentialportion thereof to dene a pair of external shoulders, a triple-laminatereinforcing member secured on the external surface of said tion parallelto the major circumferential direction of the tube and the centerlamination comprising a rubberlike matrix having a plurality ofside-by-side, elongated, substantially non-stretchable plastic elementsembedded therein and extendingat a substantial angle to said majorcircumferential direction, and an outer tubular envelope of stretchableelastic material secured on said reinforcing member and said thickenedportion of the inner envelope.

7. In an inner tube, an inner tubular envelope of stretchable, elastic,gummy material externally thickened at the inner major circumferentialportion thereof to deline a pair of external shoulders, atriple-laminate reinforcing member secured on the external surface ofsaid able, said cord elements extending at a substantial angle to saidmajor circumferential direction, and anV outer tubular envelope ofstretchable elastic material secured on said reinforcing member and saidthickened portion of the inner envelope.

8. In an inner tube, an inner tubular envelope of stretchable elastic,gummy material externally thickened at the inner major circumferentialportion thereof to dethe major circumferential direction of the tube andanv other of whlch comprises a rubber-like matrix having a plurality ofside-by-side plastic strip elements embedded therein, said stripelements being substantially nonstretchable longitudinally thereof andextending at right angles to said major circumferential direction, andan outer tubular envelope of stretchable elastic material secured onsaid reinforcing member and said thickened portion of the innerenvelope.

References Cited in the ile of this patent UNITED STATES PATENTS

